Flipkart — Serial number mismatch on product and invoice

I ordered an apple pencil for which I received an invoice with a serial number that doesn’t match with the product serial number.
The pencil has stopped working and to claim the warranty from Apple they want the correct invoice.
I have been contacting customer service since 6 days and have still not received the correct invoice. As a customer I am really dissatisfied being a flipkart plus member, I have lost trust in the organisation.
I am given false promises but not got any resolution from your side. As a customer it is my right to posses the correct invoice and it is required urgently to get the pencil replaced. Your product, invoice and customer service is just wasting my time and causing distress.